Butterfly dampers for installation in duct work through which air and/or gases will be flowing, have been previously installed. However, none of these previously installed butterfly dampers are believed to be leak free butterfly dampers.
In contrast to these butterfly dampers used in stopping air and/or gas flows, while still allowing some leakage, butterfly valves used in stopping liquid flows are provided to stop liquid flows without leakage. For example, butterfly valves are provided by the Norris/O'Bannon division of the Dover Corporation of Tulsa, Okla. and designated as Norris Butterfly Valves. An elastomer lined R-Series, inclusive of R 1000, R 2000, and R 3000 valves, referred respectively as wafer span type, double rib type, and full lug type, are available in sizes from two inches to thirty-six inches. The liquid pressure rating is two hundred pounds per square inch. The temperature range is minus thirty five degrees to positive two hundred and fifty degrees Fahrenheit. The valve bodies, depending on type, are made from cast iron, ductile iron, cast steel, bronze, and aluminum. Each valve body on the inside is isolated from the flow stream of a liquid by a resilient elastomer link, or seal, and O-ring seals. An angle-disc, i.e. an angle-blade, construction gives a three hundred and sixty degree uninterrupted contact of the disc, i.e. the blade, with the seat provided by using the resilient elastomer material. The disc, i.e. the blade, does not seat in the shaft holes, thereby assuring a bubble tight shutoff of the liquid flow, with no scrubbing of the elastomer in the shaft hole area. Shafts holding and positioning the disc, i.e. blade, are double O-ring sealed to prevent leakage into shaft bearing areas. If needed a field-replaceable resilient seat is bonded to a rigid backing ring to prevent this resilient seat from distorting or collapsing due to high velocity flow of the liquids, or in vacuum service, and during installation. Body O-ring flange seals are used to eliminate the need for flange gaskets. These flange seals can be replaced without dismantling this butterfly valve and replacing the seat. These Norris Butterfly Valves are used in oil-field drilling and production applications, in shipboard ballast systems, cargo handling systems, cooling water systems and as machinery valves.
In respect to U.S. patents finally considered at the conclusion of a U.S. Patent Search:
In 1969 in U.S. Pat. No. 3,485,476, James E. Hemphill illustrated and described his butterfly valve having a symmetrical valve disc, i.e. blade, provided with a fin configuration on both sides for reducing the hydrodynamic torque on the valve disc, so as to reduce the torque necessary to position the valve disc within the flow passage in the valve housing;
In 1970, in U.S. Pat. No. 3,502,299, Donald R. Phillips disclosed his resilient liner for butterfly valves, which he noted is an improved resilient liner in respect to one disclosed in U.S. Pat. No. 3,314,641. The valve body has an internal receiving space to receive resilient lining material. The overall configuration is such that the cold flow of the resilient material is effectively utilized to seal the resilient material, formed as the liner, against the valve body, and the internal receiving space thereof. Importantly, when achieving this sealing, the cold flow of the sealing material is prevented from materially effecting the internal diameter of the disc, i.e. blade, engaging portion of this resilient material liner. To accomplish this result, the overall resilient seat is composed of two basic elements. One element is an enclosed reinforcing member made of hard rubber, plastic, metal or so forth, and it is tubular in configuration. The other element is an encompassing resilient tubular liner member, which encompasses the reinforcing member, as these two elements are positioned in the internal receiving space of the valve body;
In 1971, in U.S. Pat. No. 3,641,360, Domer Scaramucci. illustrated and described his disc valve assembly with a tilt-in valve member. His valve can be quickly and easily assembled and disassembled, thereby facilitating the manufacture and field repair of his disc valve assembly. Further, since the disc valve member, and the seat assembly for it, are both insertable axially, via the same end of the valve body, both components can be removed from the valve body, by simply removing one flange, thereby reducing the time required during field repair of the valve assembly;
In 1972, in U.S. Pat. No. 3,656,712, Bradley E. Bertrem disclosed his butterfly valve for mounting between removable flanges. Also one of the two flanges can be removed when the valve stays closed, while retaining fluid pressure in the flow passageway. In providing his butterfly valve, he included a resilient liner of a length equal to or less than the length of the butterfly valve body, so no part of the resilient liner extends beyond the butterfly valve faces. This resilient liner included two portions. The first portion, which is not resilient, is an outer circumferential portion or backing ring made of metal or of some non-metallic material such as plastic. This backing ring is stiff to lend strength and support to the overall liner. The second portion is an inner circumferential resilient portion, which encompasses most of the backing ring and determines the flow passageway, having a reduced internal diameter resilient portion, thereby forming a valve seating resilient surface portion. When the disc, i.e. blade, of his butterfly valve is rotated to the closed position, its annual seating non-resilient surface is engaged into full sealing contact with the reduced internal diameter resilient portion of the second portion of the overall liner;
In 1972, in U.S. Pat. No. 3,666,235, Arthur A. Scott illustrated and disclosed his throttling butterfly valve. The strong housing has a seat contoured along a generally frusto or semi-spherical surface, which includes a throttling slot. The disc, i.e. blade, is made of at least two portions. One portion is a disc-like metal insert welded to a metal shaft. The other portion is a resilient material molded about the metal insert and formed to have a frusto-conical outer wall, having, in turn, a sealing lip. When the disc, i.e. blade, is rotated, the sealing lip fully contacts the frusto or semi-spherical surface of the housing, i.e. body portion, of this butterfly valve, to thereby completely stop the flow of fluid through this throttling butterfly valve;
In 1975, in U.S. Pat. No. 3,910,555, Brad E. Bertrem and Dennis L. Young disclosed their butterfly valves disc with a dovetail groove. Their patent is assigned to the Dover Corporation of Tulsa, Okla., which has the division known as Norris/O'Bannon. The valve products are referred to as Norris Butterfly Valves. In their patent they describe how a metal disc, i.e. blade, has a dovetail groove in the circumferential edge thereof to receive and to position a compliant member in the form of a torous having an original circular cross-section, receiving ninety percent of the volume of the torous member. The dovetail groove has: an entrance section having sidewalls parallel to the plane of the disc; then a diverging section with sidewalls at an angle of thirty degrees to the plane of the disc; a converging section with the sidewalls approximately forty-five degrees to the plane of the disc; and the bottom of the groove is of a circular cross-section tangent to the walls of the converging sections. The extending ten percent of the original torous compliant member makes the sealing contact with a metal seat.
In a brochure this Norris Butterfly Valve is referred to as a metal seated butterfly valve, which incorporates an elastomeric O-ring seal in the periphery of the disc edge. A metal insert space, referred to as a seat, is machined for the O-ring to be seated therein. In the same brochure, resilient seated butterfly valves are illustrated and described, wherein the entire seat is made of a resilient material, specially formed to be contacted by the periphery of an angularly positioned and moved disc, which, when seated on the resilient seat, creates a positive, bubble tight shutoff of the liquid flow, with a three hundred and sixty degree uninterrupted contact between the angle disc and the rubber seat. Because the flow stream never touches the body of this butterfly valve, there is no need for having a costly high-alloy body, even in corrosive service. The resilient elastomer seats, which are highly resistant to deterioration, are easily replaced on-site in minutes;
In 1976, in U.S. Pat. No. 3,960,177, Hans D. Baumann illustrated and described his low torque and low noise butterfly valve disc of an oval shape. This disc is mounted for rotation, so this disc is tilted, when in the closed position. The disc has a flat machined rim for closely contacting the inner wall of the bore of this butterfly valve;
In 1977, in U.S. Pat. No. 4,022,424, Donald H. Davis and John G. Mossey, disclosed their shaft bearing and seals for butterfly valves used to control the flow of steam, having multiple pressure chambers, seals, and a bearing, which collectively make an effective overall shaft end seal, even in the presence of flexures of the shaft;
In 1984, in U.S. Pat. No. 4,489,917, Hans D. Baumann illustrated and described his low torque valve disc for lined butterfly valves. The rubber lining extends the full flow length of this valve metallic housing. The disc, i.e. blade, has an oval shape and a flat rim, in turn having a slightly rounded corner. This corner is the terminating outer periphery of the disc, which makes the sealing contact with the inner resilient wall of this butterfly valve, when the disc is in a tilted closed position.
In 1990, in U.S. Pat. No. 4,917,350, Barry C. Beyer and Thomas M. Pendergrass disclosed their gasketless air damper installed in room circulating air ducts of a ventilation system of a building, wherein one thermostat is used to control the temperature in several different rooms. Their gasketless air damper quietly modulates the airflow to a room, and when necessary is closed, creating a tight mechanical seal with low air leakage. There are no discrete gaskets or seals, which otherwise would be capable of becoming loose or worn with the passage of time; and
In 1992, in U.S. Pat. No. 5,102,097, Brian K. Davis, Marshall U. Hines, Larry K. Ball, and Stephen R. Cronenberg, illustrated and described their butterfly valve with a plural-fence modular plate. They selectively added rim like portions, they called fences, to the periphery of their flow modulator, i.e. disc, i.e. blade, to achieve substantial reductions in the aerodynamic or hydrodynamic torque exerted on the modulator.
This background information derived from the Norris Butterfly Valves brochure and the selected U.S. Patents, provides the understanding of how butterfly valves used in controlling both air and/or gases, and liquids have been made with metallic components, often machined, and with resilient material components, often specially formed recesses or seats, which in turn were specially cast or machined.
There remains a need, however, for a comparatively lower cost, easily manufactured, quickly installed, freely operated, highly reliable, zero leakage butterfly valve for controlling and stopping the flow of air and/or gases, often susceptible of carrying abrasive particles and corrosive substances in duct work. Moreover, preferably, the butterfly damper body, blade, shaft, and connecting parts can be made out of all types of thermo-setting resin plastics, all types of thermoplastic materials, urethane, and castable plastics and rubbers, as all respective specifications and service environments for the butterfly damper may call for.